Fluorescent lamps require an electromagnetic ballast coil (inductor) having a circuit for limiting the current flow to the lamp. To protect the electrical ballast from the elements, prior outdoor fluorescent floodlights shelter the ballast in the same housing or hood of the fixture as the reflector and the lamp. This results in space being wasted in the hood for holding the ballast--which space, if somehow made available, could better be used either for accommodating a larger reflector or for making the fixture smaller overall. Furthermore, the ballast gives off a relatively large amount of heat, which heat can cause problems when confined within the hood of the fixture. To prevent warping or melting, plastic fixtures may require an open area around the ballast, or other type of heat sink. This results in even more wasted space and design clutter.
An additional problem with the accumulation of heat within the hood is that the light output of the fluorescent lamp will decline.
With or without a metal heat sink, the considerable weight of a ballast makes the hood top-heavy. Since such hoods typically are rotatably adjustable about an arc in a vertical plane, gravity readily will cause top-heavy hoods to fall down out of position should the pivot joint be at all loose. Over time, vibration can cause such joints to come loose, necessitating adjustment of the hood. Considering that many of these flood lights are installed in out of the way locations, such as on elevated billboards, this can be a very time and labor consuming process.
Additionally, the heating of the interior of the hood which does occur can cause the reflector lens to fog up, due to the expansion and contraction of the excessive air volume of prior art fixtures. To prevent this, the hood may require open grills, weep holes, or other types of ventilation--resulting in loss of water repellency. Few, if any, out-door fluorescent floodlights are UL (Underwriters Laboratory) "wet-location listed." None so listed are known to the present inventor.
Commonly, the hood of a prior art floodlight is attached to a screw-biased knurled pivot joint, known in the art as a "knuckle," which knuckle joint allows the direction, of the light beam to be rotatably adjusted about the transverse pivot axis of the joint (typically upward and downward, as noted above). This pivot joint also functions as a bracket for attaching the fixture to a stake or pipe in the ground, through which protective ground pipe and knuckle is led the conductive electrical wiring.
Prior art knuckles may be described as comprising a bottom pipe to which is attached a first (usually bottom-most) knurled flange. A second (usually topmost) knurled flange mates with the first. The latter is pivotally rotatable about a transverse axis passing through both flanges. Rotational adjustment is accomplished by loosening a bolt whose axis coincides with said transverse pivot axis and which bolt holds the two flanges together. The top flange leads to a top pipe, or other hollow channel, which communicates with the interior of the hood of a prior art floodlight. Fully-sheltered electrical wiring passes from the ground pipe through the hollow bottom pipe, thence through the flanges, through the hollow top pipe, and finally into the hood of the fixture, where it is attached to a ballast contained within the hood.
Prior developments in this field may be generally illustrated by reference to the following information disclosure statement:
______________________________________ Patent No. Patentee Issue Date ______________________________________ 4,782,428 R. Lowell et al. Nov. 01, 1988 4,779,178 R. Spitz Oct. 18, 1988 4,323,953 M. Hutchison Apr. 06, 1982 4,495,443 J. Cummings Jan. 22, 1985 4,713,019 E. Gaynor Dec. 15, 1987 3,254,205 D. Cobb May 31, 1966 3,833,801 T. Trevithick Sep. 03, 1974 2,347,174 K. Cross et al. Apr. 25, 1944 4,691,267 D. Giesberg Sep. 01, 1987 3,112,891 C. Cutler Dec. 03, 1963 ______________________________________
U.S. Pat. Nos. 4,782,428 and 4,779,178 teach fluorescent light fixtures that are adjustably supported. Both have the ballast outside the light hood near to a pivot flange. In the case of the '428 patent, the ballast 14 is affixed to the pivot clamp 18a and rotates therewith. However, that particular pivot clamp is not associated with the post 4. Importantly, the wire 42 thereof does not lead through the inter:Lot of the pivot clamps or the pipe and, thus, would be exposed to the elements during outdoor use.
U.S. Pat. Nos. 3,254,205 and 4,323,953 teach adjustable fluorescent floodlights.
U.S. Pat. Nos. 3,833,801 and 2,347,174 teach fluorescent lights where the ballasts are in compartments separate from the lamps.
The rest of the patents are representative of what is in the art.